SMA is one kind of RF coaxial connectors that is widely applied, with small-sized thread coupling. Characteristic impedance is 50Ω. The characteristic of connector is in wide frequency range, excellent performance, high reliability. They are used in connection with RF cable of micro-strip line in RF circuit of the WLAN system, controlled program, microwave equipment and the digital communication system. They frequency can be up to 18GHz by using semi-rigid or semi-flex cable.